Telescopic fluid feed lines

ABSTRACT

TELESCOPIC FLUID FEED LINES FOR CONVEYING HYDRAULIC FLUID TO AND FROM A REMOTE LOAD CONSISTING OF AN OUTER TUBE TELESCOPICALLY RECEIVING AN INNER TUBE WITH AN ANNULAR PISTON ON THE END THEREOF SLIDABLE ON A ROD SLEEVE FIXED WITH RESPECT TO THE OUTER TUBE, THERE BEING PROVIDED AN AREA ON THE PISTON WHICH IS SUBJECTED TO FLUID UNDER PRESSURE FOR THE PURPOSE OF MINIMIZING THE COMPRESSIVE FORCES ON THE INNER TUBE WITH THIS AREA BEING EQUAL TO THE AREA OF THE STATIONARY SLEEVE FOR THE PURPOSE OF BALANCING THE HYDRAULIC FORCES ACTING ON THE INNER TUBE.

Sept. 20, 1971 J. 1'. PARRETT TELESCOPIC FLUID FEED LINES Filed April 25. 1969 QN M w 1% %W v Q N\\ NW A Q ww Q mw N. R% U, 1mm W NR mm x .m.% R .N \w A Q 2 w n m\ aw mu u k w; m wwwww. W NW WNW \m & m m n E m i M W ww um w\ .3 h b\ \1 N 9% m Patented Sept. 20, 1971 3,605,563 TELESCOPIC FLUID FEED LINES John T. Parrett, Benton Harbor, Mich., assignor to Koehring Company, Incorporated Filed Apr. 25, 1969, Ser. No. 819,402 Int. Cl. F161 27/12 U.S. CI. 91-462 6 Claims ABSTRACT OF THE DISCLOSURE Telescopic fluid feed lines for conveying hydraulic fluid to and from a remote load consisting of an outer tube telescopically receiving an inner tube with an annular piston on the end thereof slidable on a rod sleeve fixed with respect to the outer tube, there being provided an area on the piston which is subjected to fluid under pressure for the purpose of minimizing the compressive forces on the inner tube with this area being equal to the area of the stationary sleeve for the purpose of balancing the hydraulic forces acting on the inner tube.

BACKGROUND OF THE PRESENT INVENTION In the past various types of fluid feed lines have been provided for supplying fluid to a remote but movable hydraulic motor, such as a hydraulic tool on the end of an extensible boom. One device employed in the past for this purpose is commonly known in the art as a hydraulic, telescopic feed line. Usually two of these feed lines are provided, one for supplying fluid to the motor and one for returning fluid from the motor. These feed lines find their principal use on mobile cranes and derricks. One type of such equipment utilizes the telscopic boom in which the boom tip may be extended or retracted axially to vary the length of the boom to match operational requirements. oftentimes, such equipment utilizes hydraulically driven tools suspended from the boom tip. To convey motive fluid from the base of the boom to these power operated tools it has been conventional to employ either flexible fluid feed lines or rigid telescopic feed lines having sections fixed respectively to the movable portions of the boom permitting the boom to be extended or retracted independently of the operation of the hydraulic tools.

Another application for feed lines, particularly of the rigid telescopic type, is in connection with out-rigger cylinders which are used to stabilize mobile equipment to prevent tipping or overturning thereof.

In most of these prior known telescopic feed lines a rigid inner tube is provided slidable within a rigid outer tube in telescopic fashion. A severe limitation on the utility of these telescopic feed lines is that the end of the inner tube is subjected to hydraulic fluid pressure within the tubes and forms what might be termed a hydraulic actuator which tends to separate the inner tube from the outer tube. The force created by this hydraulic actuator action in feed lines tends to buckle the extending portion of the inner tube by a column compressive force action. While it is theoretically possible to strengthen the inner tube to withstand this column compressive force this has not proved to be a desirable solution.

One solution to this problem is disclosed and described in my prior Pat. 3,318,199 assigned to the assignee of the present invention. In my prior patent I have described a telescopic feed line in which the inner telescopic tube has an enlarged piston at one end thereof slidable within a sleeve within the outer tube of the feed line with the chamber between the inner tube and this intermediate sleeve defining with the piston a chamber. By pressurizing this chamber the inner tube is subjected to a force which tends to contract it with respect to the outer tube thereby placing the inner tube under tension. At the same time the other side of the piston on the inner tube is continuously communicated with a low pressure source. With this construction the inner end of the inner tube is continuously subjected to an inward force whereby the entire tube is placed under tension thereby eliminating the tendency of the inner tube to collapse.

While the construction shown in my prior patent has been found very desirable in many applications it has the disadvantage when pressurized of the inner tube being continuously urged inwardly with respect to the outer tube so that in the absence of a counteracting force the feed tubes will contact with respect to one another. Moreover, in this prior construction it is also required that the fluid partake a tortuous path within the feed tube assembly and this is somewhat of a disadvantage because it inhibits the free flow of fluid through the feed tube assembly.

SUMMARY OF THE PRESENT INVENTION In accordance with the present invention a feed tube construction of the type generally described above is provided, but in which the inner tube is balanced with respect to the outer tube so that there is no tendency for the inner tube to contract or extend with respect to the outer tube and moreover, provision is made at the same time for relieving any column or compressive load on the inner tube. This is achieved by providing an annular piston on the end of the inner tube which slides between the outer tube and a sleeve fixed with respect to the outer tube and which normally carries the hydraulic fluid through the outer tube. The side of the piston opposite the inner tube defines a chamber between the sleeve and the other tube that is continuously communicated with low pressure to relieve any column forces on the inner tube. At the same time the chamber defined on the inner side of the piston between the inner tube and the outer tube is pressurized whenever the feed tube is pressurized placing an axial tension force on the inner tube. To balance this axial inward force which tends to contract the inner tube, fluid pressure is also exposed to the end of the sleeve and this reacts against the projecting end of the inner tube tending to urge the inner tube outwardly from the outer tube. By sizing the second chamber between the inner tube and the outer tube so that it is equal in area to the diametral area of the inner sleeve, the inner tube is balanced in all positions even when extending, and distending with no axial compressive load on the inner tube.

A further advantage of the present construction is that while a fluid chamber is provided for biasing the piston associated with the inner tube that the hydraulic flow through the feed tube assembly itself occurs through the inner sleeve axially and then axially in the same direction through the inner tube to the load, or conversely through the inner tube to the sleeve and back to a suitable tank. Thus, the flow through the feed tubes is unidirectional and the pressurizing chamber for biasing the piston does not necessitate a tortuous path for the fluid flowing through the feed tubes.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal section of one feed tube according to the present invention shown in association with a boom actuator illustrated in reduced, fragmentary, form; and

FIG. 2 is a fragmentary section taken generally along line 22 of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing a feed tube assembly 10 is shown associated with an extensible boom 12. The boom is shown merely in diagrammatic form in FIG. 1 and in reality the boom would be significantly larger than the feed tube 10.

The boom 12 consists of a relatively stationary member 14 which may have some pivotal movement, but no translating movement and a relatively extendible member 15. Carried at the end of member 15 is a hydraulic tool 16 supported by a suitable mechanical interconnection with the boom member 15 as shown at 18.

There are provided two feed tubes even though only one is shown in FIG. 1. Each of the feed tubes is adapted to either convey or return fluid to drive the motor associated with tool 16 in either direction.

For example, fluid may be delivered through line 20 through the feed tube 10 shown on the drawing, through a suitable passage 22 to the motor associated with tool 16. Fluid is returned from the motor associated with tool 16 through a passage 24, through another feed tube identical to tube 10 and connected to the boom 12 in the same fashion, and hence through a conduit 25, through control valve 27 to a suitable tank indicated at 28.

If it is desired that the tool 16 be rotated or reciprocated in the opposite direction valve 27 may be shifted to supply fluid through conduit 25, through the feed tube not shown in the drawing, through passage 24 to the motor associated with tool 16. Passage 22 then serves as a return conduit delivering fluid back through the feed tube 10 in the opposite direction, through line 20 and valve 27 to tank 28. Passage 31 communicating with valve 27 is adapted to be connected to a suitable source of supply fluid under pressure. Valve 27 may take the form of a conventional four-way spool valve.

The feed tube assembly 10 is seen to consist generally of an outer tube assembly 32 and an inner tube assembly 33. The outer tube assembly is connected by suitable mechanical interconnections such as shown at 34 to the relatively stationary boom section 14 while the inner tube assembly 33 is connected to boom section by a suitable mechanical interconnection shown at 37.

The outer tube assembly is seen to consist of a main cylindrical sleeve 40 having a generally annular porting member 41 welded as at 42 to the right end thereof. Fixed to the annular porting member 41 is an annular stepped end cap 43 having a threaded central opening 44 suitably connected to conduit 20. Fixed to annular member 41 is an elongated sleeve 45 seated within a counterbore 47 centrally disposed in the annular member 41, The interior of sleeve 45 freely and continuously communicates with passage through diagonal passages 52 in the annular member 41 which freely communicate with the interior 54 of end cap member 43. Thus, fluid flowing in either direction from passage 20 will pass through the interior of sleeve 45 and diagonal passages 52. At the other end of the sleeve is an annular fitting and sealing assembly 56 consisting of an annular ring 58 welded to sleeve 40 and threadedly receiving an internal ring member 60 which closely and slidably receives the inner tube assembly 33. Suitable seals as shown at 62 are provided within recesses in the ring 60 for the purpose of sealing the inner tube with respect to the outer tube assembly.

The inner tube assembly includes an elongated cylindrical sleeve 66 having a fitting 68 fixed to the projecting end thereof with a suitable threaded portion 69 adapted to receive a fitting (not shown) associated with passage or conduit 22.

The other end of sleeve 66 is reduced and threaded as shown at 69' and receives a stepped annular piston member 71 which slidably engages both the outer periphery of sleeve member and the inner surface of the outer tube sleeve 40. Piston 71 has a seal 72 on the inner surface thereof and piston rings 73 and 74 seated in outer grooves therein and slidably engaging the sleeve 40.

For the purpose of guiding the inner tube and locating the end of the sleeve member 45' a ring 77 is seated within a suitable recess within the end of sleeve member 45. The ring 77 has a plurality of axial grooves 80 therein as shown clearly in FIG. 2 which permit free fluid communication between the interior of tube 33 on the left side of the end of member 45 and the chamber 83 de fined between the sleeve 45 and the sleeve 66 of the inner tube assembly 33.

The piston 71 is subjected to fluid pressure whenever the feed tube 10 conveys fluid under pressure for the purpose of placing the inner tube assembly 33 under tension to minimize the column or compressive forces on the sleeve 66. Toward this end the chamber 83', which as noted above is pressurized whenever the feed tube is pressurized, freely communicates with the chamber 85 defined between the sleeve 66 and the outer sleeve 40 through ports or passages 88 in the sleeve 66. Thus, there is an effective annular area designated 90' in the drawing which determines the biasing area and force urging piston 71 and the entire inner tube assembly 33 inwardly between sleeve 45 and sleeve 40 toward member 41.

To eliminate the compressive force acting on the piston 71 and sleeve 66, chamber 91 on the other side of piston 71 between sleeve member 45 and sleeve 40', continuously communicates with low pressure either through a port 92 in sleeve 40 or through a passage 93 in annular member 41 which communicates with a low pressure valve 95 seated lWlihlI'l annular member 41.

Port 92 is connected through a suitable passage (not shown) to the corresponding port in the other feed tube. Thus, when the feed tube shown in the drawing is conveying high pressure to the tool 16 chamber 91 will communicate with low pressure through port 92 and the chamber 91 associated with the other feed tube which is then at low pressure. Conversely, when the other feed tube is the high pressure delivery tube and the feed tube shown in the drawing is the low pressure one of the feed tubes, passage 20 will of course be a low pressure return passage and spring 97 will open valve 95 permitting chamber 91 to communicate with low pressure through passage 93, across valve 95 and into the low pressure interior of end cap 43. At the same time the chamber 91 associated with the other feed tube (noting that valve 95 associated with the other feed tube would be closed due to the pressurization of line 25) communicates with low pressure through port 92, passages 93 and open valve 95.

Thus, it may be seen that the right end of piston 71 is never subjected to fluid under pressure and the compressive force on the inner tube is eliminated.

For the purpose of balancing the hydraulic forces acting on the inner tube assembly 33 the area defined by the diameter indicated at 99 of the outer diameter of sleeve member 45 is equal to the area 90 between sleeve 66 and sleeve 40. The area 99 represents the eifective hydraulic area acting on the projecting end of the inner tube assembly tending to extend the inner tube assembly from the outer tube assembly 32'. Thus, the axial forces acting on the tube assembly 33 are balanced and there is no tendency for the inner tube assembly to extend or contract with respect to the outer tube assembly, while at the same time the inner tube assembly is subjected to no compressive loads since chamber 91 is always at low pressure.

An additional advantage in the present construction is that fluid may flow directly through the feed tubes 10 without any reversal through passages therein. That is, fluid, for example, may flow through passage 20 into the interior 54 of cap 43 through passages 52 into the interior of sleeve member 45, directly into the interior of sleeve 66, through fitting 68 to the tool '16. There is no circulation of fluid through chamber 85 and port 88 and the change in volume thereof with the extension ofthe inner piston assembly is very small compared with the flow of fluid through the feed tube so that it has no significant elfect on the volume of fluid flowing through the feed tubes.

In operation, (when tube 10 is the high pressure feed tube, line 20' is pressurized by control valve 20 and high pressure in end cap 43 closes valve 95 and fluid is delivered through the feed tube through passages 52, sleeve 45, the inner tube assembly 33 and out fitting 68 to the tool .16. At the same time, fluid under pressure pressurizes chamber 85 urging piston 71 inwardly but this is offset by fluid pressure reacting against area 99 and acting on the inner feed tube assembly in the opposite direction thereby balancing the same. Chamber 91 communicates with low pressure through port 92 through the other feed tube not illustrated. Fluid is returned from the motor tool 16 through passage 24, the feed tube not shown in the drawing, passage 25, valve '27 to tank 28.

Conversely, when the other feed tube is pressurized by line 25, fluid is returned from the tool 16 through passage 22, the inner tube sleeve 66, sleeve member 45, passages 52 in end cap 43, and passage or conduit 20, across valve 27 to tank 28. Under these conditions chamber 9 1 communicates with low pressure through valve 95 which is then open under the influence of spring 97 since a low pressure condition exists in interior 54 of end cap 43.

What is claimed is:

1. A feed tube combination for supplying fluid to a load, comprising: first tube means, valve means adapted to connect said first tube means selectively to a source of supply fluid, or to drain, second tube means disposed in telescopic relation with said first tube means, means adapted to connect said second tube means to a load, and means for substantially balancing the axial forces acting on the inner one of said tube means even during relative movement between said tube means, a tube member fixed with respect to the outer one of said tube means and telescopically received in said inner tube means, piston means on the end of said inner tube means defining first and second fluid chambers on the opposite sides thereof between said tube member and said outer tube means, said first chamber if pressurized tending to extend tube means, said second chamber when pressurized tending to contract the tube means, means continuously communicating said first chamber with low pressure, including second valve means connecting said first chamber with said first valve means when the first valve means is connected to drain, port means for communicating said first chamber with low pressure when the first valve means is connected to the source of supply, said means for balancing the axial forces including the effective areas of fluid pressure in said second chamber acting on said piston means being substantially equal to the effective area defined by the outer diameter of the tube, and means for continuously pressurizing said second chamber whenever the means connecting the tube means to supply fluid is pressurized.

2. A fluid feed line assembly, comprising: an outer tube, first valve means connecting one end of said outer tube to a source of fluid under pressure or to drain, a sleeve member fixed within said outer tube and communicating with said connecting means so that the interior of the sleeve member may be pressurized, an inner tube slidable between said outer tube and said sleeve and projecting from the outer tube, said inner tube being connected to deliver fluid to a load, piston means on said inner tube sealingly and slidably engaging the outer tube and the sleeve mem her, said inner tube and outer tube defining a chamber which when pressurized acts on said piston means tending to draw the inner tube inwardly, means communicating the interior of said sleeve member with said chamber so that said chamber is at substantially the same pressure as said source of fluid under pressure, and means maintaining the side of said piston means opposite said chamber at substantially atmosphere pressure, including pressure responsive second valve means for connecting the side of the piston means opposite said chamber with said outer tube when the first valve means connects the outer tube to drain, means for connecting the side of the piston means opposite said chamber with low pressure when the outer tube is connected to the source of supply, the effective area of fluid in said chamber acting on said piston means being sub- -force acting on said inner tube.

3. A fluid feed line assembly comprising: an outer tube, first valve means connecting one end of said outer tube to a source of fluid under pressure or to drain, a sleeve member fixed within said outer tube and communicating with said connecting means so that the interior of the sleeve member may be pressurized, an inner tube slidable between said outer tube and said sleeve and projecting from the outer tube, said inner tube being connected to deliver fluid to a load, piston means on said inner tube sealingly and slidably engaging the outer tube and the sleeve member, said inner tube and outer tube defining a chamber which when pressurized acts on said piston means tending to draw the inner tube inwardly, means communicating the interior of said sleeve member with said chamber so that said chamber is at substantially the same pressure as said source of fluid under pressure, and means maintaining the side of said piston means opposite said chamber at substantially atmosphere pressure including pressure responsive valve means for connecting the side of said piston means opposite said chamber to said one end of the outer tube when the first valve means connects said one end ,of the outer tube to drain, means for connecting said side of the piston means opposite said chamber to low pressure when the first valve means connects said one end of the outer tube to the source of supply, the effective area of fluid in said chamber acting on said piston means being substantially equal to the area defined by the outer diameter of the sleeve member to substantially balance the hydraulic force acting on said inner tube, the area between the inner and outer tubes being substantially equal to the area defined by the revolution of the outer diameter of the sleeve member.

4. A feed tube assembly comprising: an outer tube, an inner tube telescopically received in said outer tube, piston means on said inner tube, means for pressurizing said piston means in a direction tending to retract the tubes whereby any tendency to collapse the inner tube compressively is reduced, means for supplying fluid through said tubes to a load without reversing the direction of fluid flow in the tubes, said means for supplying fluid through said tubes including a sleeve member fixed with respect to said outer tube and extending within said inner tube, said outer tube having means communicating the interior of said sleeve member with a source of fluid under pressure, first valve means selectively communicating the interior of the sleeve with fluid pressure of drain, the interior of said sleeve member freely communicating with the interior of said inner tube, means for pressurizing said piston means including a chamber between the inner tube and the outer tube defined in part by said piston means, port means in said inner tube communicating with the interior of said sleeve member and the interior of the second tube for conveying fluid under pressure to said chamber, means for balancing the hydraulic forces acting on the inner tube to minimize the tendency for the inner tube to retract, including the effective area of fluid in said chamber acting on said piston means being substantially equal to the area defined by the outer diameter of the sleeve member to substantially balance the hydraulic force acting on said inner tube, and means for continuously commum'cating the side of the piston means opposite the chamber with low pressure including second valve means connecting said side of the piston means with the interior of the sleeve when the first valve means connects said sleeve with drain, and means connecting said side of said piston means with low pressure when said first valve means connects the interior of the sleeve to the source of fluid pressure.

5. A feed tube assembly as defined in claim 4, wherein said piston defines a second chamber between said sleeve 8 member and said outer tube, and means communicating References Cited said second chamber with low pressure. P

6. A feed tube assembly as defined in claim 4, wherein UNITED STATES ATENTS the area between the outer tube and the inner tube is sub- 1,513,315 10/1924 Cook 285 302 stantially equal to the area defined by the revolution of 5 the outer diameter of the sleeve member. MARTIN SCHWADRON Primary Examiner A. M. OSTRAGER, Assistant Examiner US. Cl. X.R. 285302 

